Brinellhårdhedsprøvningen

Brinellhårdhedsprøvningen is a method used to measure the hardness of materials. Developed by Swedish metallurgist Johan August Brinell in 1900, it is one of the oldest and most widely used hardness testing techniques. The test involves pressing a hardened steel or carbide ball of a specified diameter into the surface of the material being tested under a specified load. The diameter of the indentation left by the ball, along with the applied load and the ball's diameter, are then used to calculate the Brinell hardness number.

The Brinell hardness number (HBW) is expressed as the load divided by the surface area of the indentation. The formula is HBW = 2F / (πD(D - √(D² - d²))), where F is the applied load in kilograms-force, D is the diameter of the ball indenter in millimeters, and d is the diameter of the indentation in millimeters. Larger indentation diameters indicate a softer material, while smaller indentation diameters suggest a harder material. The choice of ball diameter and applied load depends on the material's expected hardness and thickness.

Brinell hardness testing is particularly suitable for materials with a coarse or heterogeneous microstructure, such as cast iron and some steels, where other hardness tests might yield less reliable results due to the large grain size. It is a destructive test, as it leaves a permanent indentation on the material. However, the indentation is relatively small and often acceptable for quality control purposes. The test is standardized internationally by ISO 6506 and ASTM E10.